John Stones is out for five weeks due to a muscle injury and Aymeric Laporte is recovering from knee surgery, leaving Nicolas Otamendi as Guardiola’s only available first-team centre back.
Manchester City could turn to teenage defenders Eric Garcia and Taylor Harwood-Bellis to fill in at centre back with two of their senior defenders sidelined with long-term injuries, manager Pep Guardiola said on Friday.
John Stones is out for five weeks due to a muscle injury and Aymeric Laporte is recovering from knee surgery, leaving Nicolas Otamendi as Guardiola's only available first-team centre back.
One of Garcia (18) or Harwood-Bellis (17) could make their Premier League debut if midfielder Fernandinho, who was deployed as a makeshift central defender in Wednesday's 3-0 Champions League win at Shakhtar Donetsk, does not start in the back line.
"We don't have many other options, two young players we trust a lot," Guardiola told reporters ahead of Saturday's game at home to Watford.
"Eric was training last season with us and Harwood-Bellis trained in pre-season and we will count on them. It's not a problem, it's a challenge we have to accept and be positive. We will do it, be happy and work hard."
City beat Watford 6-0 in the FA Cup final last season to seal an unprecedented domestic treble, but Guardiola does not expect a similar result, especially after the bottom side drew 2-2 with Arsenal under new manager Quique Sanchez Flores.
"It was the last game in the season we played knowing we could be part of something unique in English football history," the Spaniard said.
"But now it's totally different. It's the beginning of the season and they've changed their manager. I saw their game against Arsenal and the second half was incredible the way they played.
"On a good afternoon they can do everything and they are strong and fast, so every game has its problems. But let's not compare with what happened in the FA Cup, I don't see any similarities."
Guardiola also hailed Gabriel Jesus' attitude after the striker, who is second choice to Sergio Aguero in the league, stepped up in the Champions League and scored in Donetsk.
"He may be involved tomorrow but it's difficult to find in Europe a player like Gabriel and how important he is," Guardiola said. "His behaviour in training is outstanding, he has to fight for his place against a legend in Aguero.
"Gabriel, be patient. I know when he plays he does absolutely everything like he has done in Ukraine, not just for the goal, the way he fights and his future at this club is incredible."